Patents on wood-burning stoves are found at dates as early as in 1874, with the Canadian Pat. No. 3,730. Throughout the other patents which exist in this field, there are the Canadian Pat. Nos. 155,216 and 176,872 and the U.S. Pat. Nos. 406,955 (dated 1889); 610,795; 1,707,096; 2,475,120; 4,127,100; and 4,230,090.
There are found in these patents a stove comprising a combustion chamber, an oven, an ash-pit, a grate made of hollow ducts assembled into a X and which open outwardly at each end, but such features do not appear concurrently.
These patents, nevertheless, present several disadvantages. Canadian Pat. No. 155,216 shows a somewhat rudimentary stove, whose minimum dimensions are too large. The walls of this stove are also susceptible of shortly warping under the warp-inducing heat produced by the combustion of wood or other, even if they are covered by an asbestos lining.
In U.S. Pat. No. 4,230,090, the ducts constituting the sides of the stove are of a small energetic efficiency, since they sustain heat losses due to their construction. To empty the ashes from the stove, one must wait that the stove be cold. The cleaning frequency would tend to be high and the cleaning is difficult in view of its access. Furthermore, this stove has no oven. The door of the combustion chamber is so low that one needs to kneel in order to position the combustible, an unpleasant operation.
In Canadian Pat. No. 176,872, the part of the stove below the grate must be cold, since it can stand directly on the ground without any legs. The calorific efficiency is thus smaller. The upper part of the stove is made of passageways of varied shapes where all the soot residues may accumulate, rendering this stove of a problematic maintenance.